By dissolving cellulose in a solvent and subsequently injecting the thus formed spinning dope through a spinneret into a spinning or coagulation bath regenerating cellulosic fibers in the form of filaments may be formed. Various solvents have been used to dissolve cellulose in the art in such processes.
As an example, processes that employ aqueous sodium hydroxide as solvent for cellulose, wherein the sodium hydroxide subsequently are reformed and recycled are known. U.S. Pat. No. 4,639,514 discloses a solvent recovery process for recovery of fresh dissolving chemicals. The process is however based on the use of acids, such as carbon dioxide, which will neutralize the sodium hydroxide, thus requiring excessive and costly causticizing with lime to restore the alkalinity of the solvent.
Thus, there is a need for an alkaline cellulose dissolving and solvent recovery process, wherein the alkalinity of the solvent is kept high throughout the whole cycle without addition of acids.